1. Field of the Invention
This invention relates to a vessel cannula and, more particularly. to a cannula having varying properties, such as rigidity or resistance to deflection, along its axial length. In one aspect, the vessel cannula has one relatively rigid portion and a second portion which is more pliable than the rigid portion. This cannula is ideally suited for use in minimally invasive cardiac surgical procedures but can be adapted for use in any fluid conducting application.
2. Description of the Related Art
Vessel cannulae have long been used during surgical procedures, such as cardiac surgery. The cannulae are typically used to provide a fluid flow path into, out of, or through a vessel, such as a coronary artery. An example of a known cannula is seen in FIG. 1 (prior art) which represents an arteriotomy cannula commercially available from the DLP Division of Medtronic, Inc. This cannula comprises a body portion A having a lumen B extending therethrough with a bulb C provided at the distal end thereof and a female luer connector D provided at the proximal end thereof. The bulb C and rigid body A are integrally molded as a single unit whereas the luer connector D is molded independently of the body and secured thereto by conventional means.
The cannula seen in FIG. 1 (prior art) is ideally suited for use in an open heart surgical procedure because the surgeon can easily place the cannula in the operative position in view of the size of the chest wall opening.
A growing surgical trend is to move away from traditional open heart surgical procedures to more less traumatic minimally invasive cardiac surgical procedures. However, known surgical equipment such as the cannula seen in FIG. 1 is not well adapted for these minimally invasive surgical techniques. During most minimally invasive surgical techniques, the size of the surgical incision in the chest wall is dramatically reduced, thereby requiring maximum efficiency in the positioning and operation of the necessary surgical equipment. The structure of the known cannula may not be best suited for use in these procedures. An arteriotomy cannula used in a minimally invasive surgical procedure must have sufficient rigidity to be insertable into the coronary artery and yet have sufficient flexibility so that the cannula will not interfere with other surgical tools inserted through the relatively small chest wall opening.